Real-time perfusion imaging and quantification

Abstract

A solution for diagnostic applications is proposed. Particularly, a corresponding diagnostic system includes means (903-906) for providing (A1-A3) a plurality of input signals representative of a body-part being perfused with a contrast agent over time, each input signal being indicative of a response to an interrogating stimulus of a corresponding location of the body-part possibly including the contrast agent, means (909-930) for generating (A4.1-A4.3) a plurality of filtered signals from selected input signals of selected locations, each filtered signal at each instant over time being generated from a corresponding selected input signal according to a portion of the selected input signal including said instant, and means (933-939) for monitoring (A4.4-A4.6) each filtered signal to detect a peak in the response to the interrogation stimulus of the corresponding selected location, the peak being detected in response to the fulfillment of a stability condition by a corresponding portion of the filtered signal.

The invention claimed is: 
     
       1. A process for generating diagnostic data from an imaging procedure, the process comprising:
 administering a contrast agent to a body-part; 
 applying an interrogating stimulus to the body-part being perfused with the contrast agent; 
 recording, into a memory of a data processing system, an input signal acquired in response to the interrogating stimulus that is applied to the body part being perfused with a contrast agent; 
 generating and storing into the memory of the data processing system a filtered signal from the input signal, the filtered signal being generated by:
 comparing the intensity of a comparison signal, equal to the input signal or to a smoothed signal obtained by applying a smoothing function to the input signal and at least one previous input signal provided during the imaging procedure, with the intensity of a previous filtered signal generated from a previous input signal provided during the imaging procedure, the previous filtered signal being set to a previous comparison signal provided during the imaging procedure at a first iteration, and then 
 if the intensity of the comparison signal is representative of a response to the interrogating stimulus that is greater than the response of the previous filtered signal, then the intensity of the filtered signal equals the intensity of the comparison signal, otherwise the intensity of the filtered signal equals the intensity of the previous filtered signal; 
 
 after a predetermined number of filtered signals have been generated, monitoring the filtered signal by the data processing system to determine whether a stability condition has been fulfilled, the stability condition being fulfilled when the intensity of the filtered signal remains within a predefined range of variation relative to the intensity of a predefined number of immediately preceding filtered signals; 
 repeating the recording, generating and monitoring acts over time until the stability condition is fulfilled, and when fulfilled, establishing a peak in the corresponding filtered signal, 
 generating and storing into the memory of the data processing system the diagnostic data according to the filtered signals and the detection of the peak; and 
 displaying at least a representation of the diagnostic data according to the deletion of the peak, on a monitor of the data processing system for evaluating the body-part. 
 
     
     
       2. The process according to  claim 1 , wherein said monitoring the filtered signal includes:
 stopping the monitoring after the stability condition has been fulfilled. 
 
     
     
       3. The process according to  claim 2 , wherein:
 said establishing a peak includes setting the peak to an instant preceding the instant at which the stability condition is fulfilled by a stability time-window corresponding to said predefined number of immediately preceding filtered signals. 
 
     
     
       4. The process according to  claim 1 , further comprising calculating at least one perfusion parameter indicative of a perfusion of the location of the body-part according to the peak. 
     
     
       5. The process according to  claim 4 , wherein said calculating at least one perfusion parameter includes:
 generating a linearized input signal from the input signal, the linearized input signal being proportional to a concentration of the contrast agent in the corresponding location of the body-part, and 
 calculating said at least one perfusion parameter according to the linearized input signal at one or more instants being determined by said monitoring. 
 
     
     
       6. The process according to  claim 4 , wherein said
 monitoring the filtered signal includes detecting an arrival instant at which the filtered signal exceeds a threshold value and establishing a peak instant indicative of an instant of detection of the peak, and calculating at least one perfusion parameter includes determining a peak value indicative of a response to the interrogating stimulus at the peak instant. 
 
     
     
       7. The process according to  claim 6 , wherein said calculating at least one perfusion parameter includes:
 calculating a wash-in rate according to a ratio between the peak value and a difference between the peak instant and the arrival instant. 
 
     
     
       8. The process according to  claim 6 , wherein said monitoring the filtered signal includes:
 detecting an arrival instant at which the filtered signal exceeds a threshold value and detecting a peak instant indicative of an instant of detection of the peak, and calculating at least one perfusion parameter includes determining a peak value indicative of a response to the interrogating stimulus of the corresponding selected location at the peak instant, and 
 detecting a reduction instant indicative of an instant of reaching of a reduction value by the filtered signal, the reduction value being a predefined percentage of the peak value. 
 
     
     
       9. The process according to  claim 8 , wherein said calculating at least one perfusion parameter includes:
 calculating a wash-in rate according to a ratio between the peak value and a difference between the peak instant and the arrival instant, 
 calculating a wash-out rate according to a ratio between the reduction value and a difference between the reduction instant and the peak instant, and 
 calculating a product between the wash-in rate and the wash-out rate. 
 
     
     
       10. The process according to  claim 1 , wherein:
 said recording an input signal includes recording a sequence of input images each one including a plurality of input signals each one indicative of the response to the interrogating stimulus of a corresponding location of the body-part, 
 said generating a filtered signal includes generating a sequence of filtered images from the input images, for each selected location each filtered image including the filtered signal being generated from the corresponding input signal. 
 
     
     
       11. The process according to  claim 10 , wherein said generating a sequence of filtered images includes, after said establishing the peak:
 comparing the intensity of the comparison signal with the intensity of the previous filtered signal and then if the intensity of the comparison signal is representative of the response lower than the response of the previous filtered signal, then the intensity of the filtered signal equals the intensity of the comparison signal, otherwise the intensity of the filtered signal equals the intensity of the previous filtered signal. 
 
     
     
       12. The process according to  claim 10 , further comprising:
 calculating at least one perfusion parameter indicative of a perfusion of the location of the body-part according to the peak, and 
 generating at least one sequence of dynamic parametric images, in each of said at least one sequence of dynamic parameter images for each location each dynamic parametric image including a null value before said calculating a corresponding one of said at least one perfusion parameter and a value indicative of the corresponding perfusion parameter after said calculating the corresponding perfusion parameter. 
 
     
     
       13. The process according to  claim 12 , wherein said generating at least one sequence of dynamic parametric images includes maintaining the null value for each location of each dynamic parametric image after said calculating the corresponding perfusion parameter when the corresponding perfusion parameter does not reach a threshold value. 
     
     
       14. The process according to  claim 12 , further comprising generating a sequence of overlaid images for each sequence of dynamic parametric images, the overlaid images being generated by overlaying each dynamic parametric image on a corresponding filtered image. 
     
     
       15. The process according to  claim 1 , further comprising:
 applying a destruction pulse to the body-part to cause a destruction of the contrast agent for at least 50% of a local concentration thereof before said applying the destruction pulse; 
 repeating, at least once:
 said recording an input signal, 
 said generating a filtered signal, 
 said monitoring the filtered signal, and 
 said establishing a peak, 
 
 after said applying the destruction pulse. 
 
     
     
       16. A diagnostic method comprising:
 administering a contrast agent to a body-part; 
 applying an interrogating stimulus to a location of the body-part being perfused with the contrast agent; 
 acquiring a plurality of input signals over a plurality of instants in time, each input signal indicative of a response to a corresponding interrogating stimulus at one of the instants in time, the plurality of input signals being processed by the process according to  claim 1  thereby displaying said representation of the diagnostic data; and 
 evaluating the body-part according to the representation of the diagnostic data. 
 
     
     
       17. A computer program product including a non-transitory computer-readable medium storing a computer program, the computer program being loadable into a working memory of a data processing system thereby configuring the data processing system to perform a process for generating diagnostic data from an imaging procedure when the computer program is executed on the data processing system, the process comprising:
 recording, into a memory of a data processing system, an input signal acquired in response to an interrogating stimulus that is applied to a location of a body part being perfused with a contrast agent; 
 generating and storing into the memory of the data processing system a filtered signal from the input signal, the filtered signal being generated by:
 comparing the intensity of a comparison signal, equal to the input signal or to a smoothed signal obtained by applying a smoothing function to the input signal and at least one previous input signal provided during the imaging procedure, with the intensity of a previous filtered signal generated from a previous input signal provided during the imaging procedure, the previous filtered signal being set to a previous comparison signal provided during the imaging procedure at a first iteration, and then 
 if the intensity of the comparison signal is representative of a response to the interrogating stimulus that is greater than the response of the previous filtered signal, then the intensity of the filtered signal equals the intensity of the comparison signal, otherwise the intensity of the filtered signal equals the intensity of the previous filtered signal; 
 
 after a predetermined number of filtered signals have been generated, monitoring the filtered signal by the data processing system to determine whether a stability condition has been fulfilled, the stability condition being fulfilled when the intensity of the filtered signal remains with a predefined range of variation relative to the intensity of a predefined number of immediately preceding filtered signals; 
 repeating the recording, generating and monitoring acts over time until the stability condition is fulfilled, and when fulfilled, establishing a peak in the corresponding filtered signal; 
 generating and storing into the memory of the data processing system the diagnostic data according to the filtered signals and to the detection of the peak; and 
 displaying at least a representation of the diagnostic data according to the detection of the peak, on a monitor of the data processing system for evaluating the body-part. 
 
     
     
       18. A diagnostic system for generating diagnostic data from an imaging procedure, the system comprising:
 a circuit for applying an interrogating stimulus to a body-part perfused with a contrast agent; 
 a circuit for recording, into a memory of a data processing system, an input signal acquired in response to the interrogating stimulus that is applied to the body part; 
 a circuit for generating and storing into the memory of the data processing system a filtered signal from the input signal, the filtered signal being generated by:
 comparing the intensity of a comparison signal, equal to the input signal or to a smoothed signal obtained by applying a smoothing function to the input signal and at least one previous input signal provided during the imaging procedure, with the intensity of a previous filtered signal generated from a previous input signal provided during the imaging procedure, the previous filtered signal being set to a previous comparison signal provided during the imaging procedure at a first iteration, and then 
 if the intensity of the comparison signal is representative of a response to the interrogating stimulus that is greater than the response of the previous filtered signal, then the intensity of the filtered signal equals the intensity of the comparison signal, otherwise the intensity of the filtered signal equals the intensity of the previous filtered signal; 
 
 a circuit of the data processing system for monitoring the filtered signal to determine whether a stability condition has been fulfilled after a predetermined number of filtered signals have been generated, the stability condition being fulfilled when the intensity of the filtered signal remains within a predefined range of variation relative to the intensity of a predefined number of immediately preceding filtered signals; 
 a circuit for causing the other circuits to repeat their respective recording, generating and monitoring acts over time until the stability condition is fulfilled, and when fulfilled, establishing a peak in the corresponding filtered signal; 
 a circuit for generating and storing into the memory of the data processing system diagnostic data according to the filtered signals and the detection of the peak; and 
 a circuit for displaying at least a representation of the diagnostic data according to the detection of the peak, on a monitor of the data processing system for evaluating the body-part. 
 
     
     
       19. The diagnostic system according to  claim 18 , wherein the circuit for monitoring the filtered signal includes:
 a circuit for stopping the monitoring after the stability condition has been fulfilled. 
 
     
     
       20. The diagnostic system according to  claim 19 , wherein:
 the circuit for establishing the peak includes a circuit for setting the peak to an instant preceding the instant at which the stability condition is fulfilled by a stability time-window corresponding to said predefined number of immediately preceding filtered signals. 
 
     
     
       21. The diagnostic system according to  claim 18 , further comprising a circuit for calculating at least one perfusion parameter indicative of a perfusion of the location of the body-part according to the peak. 
     
     
       22. The diagnostic system according to  claim 21 , wherein the circuit for calculating at least one perfusion parameter includes:
 a circuit for generating a linearized input signal from the input signal, the linearized input signal being proportional to a concentration of the contrast agent in the location of the body-part, and 
 a circuit for calculating said at least one perfusion parameter according to the linearized input signal at one or more instants being determined by the circuit for monitoring. 
 
     
     
       23. The diagnostic system according to  claim 21 , wherein
 the circuit for monitoring the filtered signal includes a circuit for detecting an arrival instant at which the filtered signal exceeds a threshold value and a circuit for establishing a peak instant indicative of an instant of detection of the peak, and the circuit for calculating at least one perfusion parameter includes a circuit for determining a peak value indicative of a response to the interrogating stimulus at the peak instant. 
 
     
     
       24. The diagnostic system according to  claim 23 , wherein the circuit for calculating at least one perfusion parameter includes:
 a circuit for calculating a wash-in rate according to a ratio between the peak value and a difference between the peak instant and the arrival instant. 
 
     
     
       25. The diagnostic system according to  claim 21 , wherein the circuit for monitoring the filtered signal includes:
 a circuit for detecting an arrival instant at which the filtered signal exceeds a threshold value and a circuit for detecting a peak instant indicative of an instant of detection of the peak, and the circuit for calculating at least one perfusion parameter includes a circuit for determining a peak value indicative of a response to the interrogating stimulus of the corresponding selected location at the peak instant, and 
 a circuit for detecting a reduction instant indicative of an instant of reaching of a reduction value by the filtered signal, the reduction value being a predefined percentage of the peak value. 
 
     
     
       26. The diagnostic system according to  claim 25 , wherein the circuit for calculating at least one perfusion parameter includes:
 a circuit for calculating a wash-in rate according to a ratio between the peak value and a difference between the peak instant and the arrival instant, 
 a circuit for calculating a wash-out rate according to a ratio between the reduction value and a difference between the reduction instant and the peak instant, and 
 a circuit for calculating a product between the wash-in rate and the wash-out rate. 
 
     
     
       27. The diagnostic system according to  claim 18 , wherein:
 the circuit for recording an input signal includes a circuit for recording a sequence of input images each one including a plurality of input signals each one indicative of the response to the interrogating stimulus of a corresponding location of the body-part, 
 the circuit for generating a filtered signal includes a circuit for generating a sequence of filtered images from the input images, for each selected location each filtered image including the filtered signal being generated from the corresponding input signal. 
 
     
     
       28. The diagnostic system according to  claim 27 , wherein the circuit for generating a sequence of filtered images includes a circuit for, after said detecting the corresponding peak, comparing the intensity of the comparison signal with the intensity of the previous filtered signal and then if the intensity of the comparison signal is representative of the response lower than the response of the previous filtered signal, then the intensity of the filtered signal equals the intensity of the comparison signal, otherwise the intensity of the filtered signal equals the intensity of the previous filtered signal. 
     
     
       29. The diagnostic system according to  claim 27 , further comprising a circuit for calculating at least one perfusion parameter indicative of a perfusion of a location of the body-part according to the peak, and a circuit for generating at least one sequence of dynamic parametric images, in each of said at least one sequence of dynamic parameter images for each location each dynamic parametric image including a null value before said calculating a corresponding one of said at least one perfusion parameter and a value indicative of the corresponding perfusion parameter after said calculating the corresponding perfusion parameter. 
     
     
       30. The diagnostic system according to  claim 29 , wherein the circuit for generating at least one sequence of dynamic parametric images includes a circuit for maintaining the null value for each location of each dynamic parametric image after said calculating the corresponding perfusion parameter when the corresponding perfusion parameter does not reach a threshold value. 
     
     
       31. The diagnostic system according to  claim 29 , further comprising a circuit for generating a sequence of overlaid images for each sequence of dynamic parametric images, the overlaid images being generated by overlaying each dynamic parametric image on a corresponding filtered image. 
     
     
       32. The diagnostic system according to  claim 18 , further comprising:
 a circuit for applying a destruction pulse to the body-part to cause a destruction of the contrast agent for at least 50% of a local concentration thereof before said applying the destruction pulse, and 
 a circuit for repeating at least once an actuation of the circuit recording an input signal, the circuit for generating a filtered signal, the circuit for monitoring the filtered signal and the circuit for establishing a peak.